436 FXUS64 KAMA 150503 AAB AFDAMA Area Forecast Discussion...UPDATED National Weather Service Amarillo TX 1203 AM CDT Sun Mar 15 2020 .AVIATION... IFR/LIFR conditions will be the rule through this forecast at all sites. Showers will move from south to north across the region this afternoon into the early evening. So have mentioned them in this forecast. Even some thunderstorms will be possible at AMA, so have mentioned thunder there. Winds will turn from the east to the southeast with speeds generally under 15 knots. && .PREV DISCUSSION... /Issued 639 PM CDT Sat Mar 14 2020/ AVIATION...00Z TAFS... VFR conditions at KAMA and DHT for maybe another 2 to 6 hours. DHT will likely go MVFR/IFR first given where the low cloud bank it holding. IFR/LIFR conditions expected the remainder of the TAF period, as low clouds and fog will role back in after 06z. Just how low the visibility will get is in question, but for now have gone a little aggressive with 1/2 mile and cigs could get down to 200ft. A quarter mile visibility can't be ruled out, but not high enough confidence at this time. Will see how the obs play out through the evening. Winds will be easterly around 10kts for the main part of the TAF period. Chances for showers will really pick up after 18z, and there could be some thunder involved. Will hold off mention of thunder for the next package, since it's 18 hour out. Weber PREV DISCUSSION... /Issued 305 PM CDT Sat Mar 14 2020/ SHORT TERM...Tonight through Sunday night... Low clouds have been stubborn to erode across the OK Panhandle and parts of the northern and eastern TX Panhandle this afternoon, with max temperatures struggling to get out of the 40s. Southwest of that area, clearing has occurred, allowing temperatures to reach into the 60s. Expect the low clouds along with areas of fog and drizzle to return to the forecast area later this evening and tonight, persisting through Sunday morning courtesy of moist low level upslope flow moving over the cool dome at the surface. Short range models are in very good agreement with this scenario and were accepted. For Sunday and Sunday night, another closed upper level low pressure system is progged to dig southward to a position off the northern CA coast by 12Z Monday morning, with further digging anticipated thereafter. Broad mid and upper level southwest flow ahead of this feature is expected durg this time period, with individual minor shortwave trofs embedded in this overall flow pattern. One such impulse is progged to track across the southern high plains Sunday afternoon and night. This will result in a threat of showers and tstms. Given the projected path of this minor upper level shortwave trof, highest pops were placed across roughly the southeast half of the fcst area, with lowest values across the far northwest sections. Precipitation is forecast to diminish from west to east late Sunday night. Short range models are in general agreement durg this time frame and were utilized. 02 LONG TERM...Monday through Friday... Synopsis: Even though Monday looks mostly dry due to brief stint of zonal flow, the moist pattern will resume through at least Wednesday due to persistent southwest flow with ample Pacific moisture plume. Medium and long term model output continue to support large closed upper low currently over Pac NW slowly moving down the CA coast through Tuesday. The low is then progged to open up and favors some negative tilt as it crosses the southwest CONUS and approaches the Panhandles Wednesday into Thursday. A lead impulse in the 500mb flow will bring precipitation chances to the area Tuesday, but the main dynamics with the upper low will not arrive until Wednesday. Thunderstorms will be possible, although there are a few factors that could limit this potential which will be discussed below. The zonal flow on Monday will help advect drier mid and upper level air into the area at least briefly. However, some lingering showers are possible in the far southeast zones Monday morning along with some fog. Deterministic models also suggest lee troughing with low level moisture left over from Sunday to help form a dryline feature Monday afternoon positioned from the central to eastern Panhandles. GFS model soundings suggest some capping in place, but do indicate steepening lapse rates and 500 to 800 J/kg SBCAPE. The NAM is much more aggressive with dry air and cap so it never generates much instability. Thus, Monday afternoon PoPs were left mostly below mentionable, but a rogue thunderstorm can't completely be ruled out along the moisture boundary. A northern stream trough crosses the Great Lakes vicinity Tuesday helping to push a weak front into the Panhandles ahead of southern stream 500mb impulse. There is some disagreement with the timing and placement of the front which will determine who has the best chance for thunderstorms as opposed to rain showers as upslope flow forms north of the front and the best moisture and thermodynamic profiles for thunder stay along and south of the front as the 500mb impulse moves through the southwest flow. Right now, it looks like the southeast and south central Texas Panhandle have the best chance of seeing some thunderstorms with some pockets of moderate to heavy rain (PWATs exceeding one inch by Tuesday afternoon). Some minor flooding issues can't be ruled out Tuesday afternoon into Tuesday night. Some fog or possibly drizzle will once again be possible in the area Tuesday given progged soundings. As mentioned before, the main upper low is expected to arrive on Wednesday which will lead to the best large scale lift of the week. However, there is some concern about low level moisture recovery which will depend on the timing of Tuesday's activity in relation to when the lift arrives on Wednesday. Healthy PoPs offered by NBM were kept, as moisture should be sufficient for at least shower activity, especially Wednesday night. The latest trends for Thursday continue to lower precip chances as a surface low forms near the Raton Mesa in response to upper level jet streak. The timing of this low as it moves across the KS plains ends up shifting the dryline east of the Panhandles by Thursday afternoon. Thus, slight chance PoPs were retained for the morning to account for any lingering activity from Wed night, but otherwise trends are shifting any new development into OK by Thurs evening. Instead, windy conditions do look likely as the surface low deepens and a Pacific front invades Thursday morning followed by a polar front Thursday night. Based on current trends, will not be surprised if wind headlines are needed Thurs into Thursday night for most if not all of the Panhandles. Long range guidance hints at another western CONUS trough reloading going into next weekend which suggest precip chances may return. Ward && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 15/3